NANOPOSITIONER APPLICATIONS
selected experimental results
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Controlling Electron Emission in Space and Time
	The dynamics of electrons emitted from a sharp tungsten tip triggered by femtosecond laser pulses have been investigated. The setup shown to the left is situated in an UHV chamber at p = 10-10 mbar pressure. A xyz positioning stack enables precision alignment of the tip. Photoelectron spectra are recorded while the phase between carrier wave and intensity envelope is varied in small steps. The lower figure shows two electron spectra, recorded with a phase difference of 180 degrees. In a), pronounced peaks are visible caused by interference of two electron wave packets emitted during subsequent optical cycles. In b), no peak structure is visible; only one electron wave packet contributes. This energy domain effect allows conclusions about the time dynamics of the electrons. By shaping the laser electric field with the carrier-envelope phase, the dynamics of the electrons can be controlled with attosecond precision. The presented system enables control over photoelectrons from a metal tip in space (nanometer scale) and time (attosecond scale). The data was kindly provided by M. Krüger, M. Schenk, and P. Hommelhoff, Max Planck Institute of Quantum Optics, Garching, Germany.
Mechanically Controlled Multi-Contact Break Junctions
	In this application, small tips made from either glass or graphite were used to locally deform a silicon membrane, creating break junctions in a very controlled fashion. The tips with a typical radius between 50 and 200 microns were precisely controlled using attocube’s nanopositioning technology. The approach of locally creating and controlling individual break junctions can be used to study the influence of optical excitations on the conductance of individual molecules and for controllable metallic single-electron transistors. Reprinted with permission from R. Waitz, O. Schecker and E. Scheer, Rev. Sci. Instrum. 79, 093901 (2008). © 2008, American Institute of Physics.
Special Micro X-ray Fluorescence Analysis (micro-XRF) Spectrometer
	Confocal micro-XRF is a method to determine the spatial distribution of major, minor and trace elements within a sample in three dimensions. The employed polycapillary x-ray optics need to be aligned precisely to get optimal results. Very compact positioners had to be used inside the vacuum chamber for this purpose. Long time stability of the alignment is also a major requisite. ANPxyz101 nanopositioners fulfill these requirements very well. The figure to the left shows a 3D sample measurement of a cross made from 10 μm copper wire which is placed on an x-ray screen and fixed using adhesive tape. The data was kindly provided by S. Smolek and C. Streli, Atominstitut of the TU Wien. S. Smolek, C. Streli, N. Zoeger, and P. Wobrauschek, Rev. Sci. Instr. 81, 053707 (2010).
Lensless Imaging with X-Ray Waveguides
	A synchrotron generated X-ray beam was coupled into an X-ray waveguide located in the focus of Kirkpatrick-Baez mirrors. The resulting filtered wave was then used to illuminate a sample coherently, yielding a magnified hologram of the sample recorded by a pixel detector. Several linear positioners, goniometers, and rotators were applied for precision alignment of the waveguide with respect to the sample, which in turn was mounted on a high-precision tomographic rotation stage. Reprinted with permission from S. Kalbfleisch et al., AIP. Conf. Proc., 1234, 433-436 (2010). © 2010, American Institute of Physics.